Shelf



FIG. 1 is a perspective view of a shelf showing our design;

FIG. 2 is a front elevation view;

FIG. 3 is a rear elevation view;

FIG. 4 is a right side elevation view;

FIG. 5 is a left side elevation view;

FIG. 6 is a top plan view; and,

FIG. 7 is a bottom plan view.

The broken lines shown in the figures represent portions of the shelf that form no part of the claimed design. 

CLAIM The ornamental design for a shelf, as shown and described. 